1. Field of Invention
The invention relates to a ratchet wheel structure and, in particular, to a one-way ratchet wheel element that has tighter engagement in operations.
2. Related Art
FIG. 11 shows a conventional one-way driving mechanism used on a wrench. One end of the wrench 91 has an accommodating hole 92 with a ratchet wheel block 93. The ratchet wheel block 93 is surrounded by several slant depressions 94. Several transmission spaces 95 are formed between the slant depressions 94 and the inner wall of the accommodating hole 92. Each of the transmission spaces 95 is disposed with a rolling column 96, which engages one side of the inner wall of the accommodating hole 92 in one way. Therefore, the wrench can drive the ratchet wheel block 93 and the element it mounts on. However, the force rests mainly on the edge of the ratchet wheel block 93 because of the structure of the ratchet wrench. It is likely to result in aberrations. Moreover, if the exerted force is too large, the rolling column 96 is likely to slip. The symmetric structure also renders a thick wrench body. The torque resistance is far lower than the conventional ratchet wheel wrench. Such a tool has to be specially treated to strengthen the structure in order to satisfy the torque resistance standard. The cost thus cannot be reduced.